Centralized traffic controlling system for railroads



June 1936- E. o. BLobGETT 7 2,042,450

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS muLzom u Q. W m mm u C INVENEZ J; 0 BY M '%u ArroRN EY Filed April 15, 1933 Patented June 2, 1936 UNITED STATES CENTRALIZED TRAFFIC- CONTROLLING SYSTEM FOR BAILROADS Edwin 0. Blodgett, Rochester, N. Y.', assignor to General Railway Signal Company, Rochester,

Application April 13, 1933, Serial No. 665,990

22 Claims.

This invention relates to railway centralized trafiic controlling systems, and more particularly to a system known as the direct control typeas I distinguished from a selector or coded type of system.

It is proposed, in accordance with the present invention, to provide a means for controlling a remote power operated track switch by distinctively selecting the direction of current in a first line circuit, and to control the traffic over the track switch by conditioning the same control line circuit in a manner that a subsequent distinctive selection or the direction of current therein may be effective to govern trafiic over that track switch in either direction. It is also proposed to provide a means for communicating over a second line circuit an indication of the operated position of the track switch, the clear or stop indication displayed by the signals associated with that track switch, and the presence or absence of a train on a detector section of track. It is further proposed to provide interlocking circuit means to prevent improper op erations of the system and still retain sufficient operating flexibility to permit efficient governing of trafiic movements.

Other objects, purposes and characteristic features of the invention will appear as the description thereof progresses, during which, references will be made to the accompanying drawing which illustrates in a diagrammatic and conventional manner one specific embodiment of the present invention which is susceptible of considerable modifications or adaptations'in practice depending on the type of controls required and the character and number of indications which are considered advantageous in the particular application.

In the accompanying drawing, a complete communicating system is shown for transmitting controls and indications between a typical outlying field station and the apparatus at the control office which is associated with this field station. It is to be understood, however, that in a practical application of this system, there will be considerable distance between a field station and the control office, and that'it is necessary to extend only three wires over this distance namely the control line wire CL, the indication line wire 1L and the common line wire C. The wire C may be the common wire for the complete centralized traffic controlling system, if so desired, or may be the common wire for only one station.

In systems having several outlying field stations, two line wires, such as CL and IL, will of (Cl; i246-3) course be required to connect each of these field stations with the control ofiice, and the field station apparatus as well as the control oflice apparatus which are designated by the legend on the drawing will also be duplicated for each of the outlying stations.

A typical section of track over which trafiic may be controlled in accordance with the present invention is diagrammatically shown at the field station as including a track switch TS arranged :to route traffic either over a main or diverging route as shown. This track switch TS is operated by a switch machine SM and suitable wayside signals ES, WS and WSA are shown in the conventional manner as governing traffic movements over this section of track.

A portion of 'a track diagram which simulates the typical section of actual track shown at the field station is illustrated at the control office. This track diagram includes an indicating light OS for indicating the occupancy of a section. of track including the track switch and a similar indicating light SK is provided for indicating the clearing of any one of the signals ES, WS or WSA.

A signal control lever SGL is employed at the control ofiice which is operable to three positions, namely west, stop and east as indicated respectively by the references W, S and E.

A switch control lever SML is also provided which is operable to two positions, N and R, for setting up a normal and reverse control for the switch machine SM. Suitable contacts are shown in the conventional manner as operated in accordance with the various positions of the control leversSGL and SML, and a third indicating light COR is provided for indicating when the operated position of the track switch TS corresponds to the position of the control lever SML.

The various relays at both the control ofiice and the field station are shown in the conventional manner, andit may be here mentioned that the relays SA, NIS and RIS at the control oifice are shown with heavy base lines to indicate that these relays are slower acting than other relays not indicated in this manner. The relay M at the field station is the conventional signal repeating relay arranged in the local signalling circuits, (not shown) to be normally onergized whenever all the signals ES, WS and WSA are displaying stop indications, but to be de-energized whenever any one of the signals displays a clear indication. The relay TR is the conventionally arranged track relay associated with a normally energized section of track including the track switch TS, and the relay track switch TS and to drop its neutral contacts whenever the switch is not in either extreme locked position by circuits not shown herein but which may be arranged as fully described in the patent to C. S. Bushnell No. 1,517,236 granted November 25, 1924.

The control and indicating line circuits are to be energized from a suitable alternating current source of energy. This source of energy is indicated as being connected to the primary of a transformer TR at the control oflice while one side of the secondary of this transformer is connected to the common line'wire C and the other side is connected to one side of each of two oppositely arranged asymmetric units or rectifiers RA and 7 .RB. At the field station, two similar rectifiers RA and RB? are each connected atone side to the common wire C,'and these rectifiers at both the control office and at the field station may be of any suitable type of asymmetric unit, such as the usual copper oxide unit, the electrolytic rectify-- ing unit, the vacuum tube unit, or any other type which may be readily'adapted to the rectification of low current values.

' The symbols and are employed to in-:

alternating current selected by the rectifying units RA and RB, a means for adapting these relaysto operate with greatest eificiency on currentof such characteristics may be necessary.

For example, a special design of the magnetic circuit may be provided in these linerelays to effect a hold over of the magnetic attraction of the armature between successive energizations of the windings by successive half cycles of the alternating current.

' Operation In the accompanying drawing, the switch con-' trol lever SML is shown in its normal position N which effects the energization of relay NC at the field station byhalf cycles of alternating current which are of a definite polarity (which for convenience may be termed polarity). The circuit for energizing relay NC may be traced from the upper terminal of the secondary of transformer TR, through the rectifying unit RA tobus A, contact 5 of leverSML in its normal position N,-wire 6, back contact I of relay SA, wires 8 and 9, control line wire CL, wire ll], through the windings of relay NCQwire ll, bus A through the rectifying unit RA and back to the lower terminal of the secondary of transformer TR over the common line wire C.

Thetrack switch TS atthe field station is also shownin the normal operated position in accordance, with the position of its' control lever SMBwhich effects the energization ofrelay NI jatthe control office by half cycles of alternating current which are of a definite polarityfiwhi'ch may be termed polarity). The energizing circuit for relay NI may be traced from the up:

- per terminal of the secondary of transformer TR, through the rectifying unit RA to bus A, wire 20, through the windings of relay NI, wire I9, indicating line wire IL, neutral front contact l8 of relay WP, polar contact l6 of relay WP in its left hand position, wires l 5 and I4, front contact I3 of relay M, wire l2, bus A through the rectifying unit RA and back to the lower terminal of transformer TR by the common line wire C. The energization of relay NI then energizes its stick repeating relay NIS over a circuit from front contact 2| of relay NI, wire 22, back contact 23 of relayRIS, wires 24 and 25, through the winding of relay NIS to Now, considering that the operator desiring to reverse the track switch TS to route traflic upon the passing siding, moves the switch control lever SML to position R. With the switch control lever SML in its'reverse position R and relay NIS en ergized, an indication at the control ofiice that the position of the switch control lever is out of correspondence with the position of the track switch is now displayed by energizing the correspondence light COR over a circuit from back contact 4| of relay RIS, wire 42, front contact 43 of relay NIS, wires 44 and 45, contact 46 of lever SML in its reverse position R, wire 41, through the indicated light COR to .The moving of the lever SML to position R for energizing relay RC may be traced from the 2? lower terminal of the secondary of transformer TR, over line wire C, through the rectifying unit RB to bus B, wire 26, through the winding of relay RC, wire 21, control line wire CL, wires 9 and 8, back contact 1 of relay SA, wire 6, contact 5 of lever SML in its reverse position R, bus B, through the rectifying unit RB to the upper terminal of thesecondary of transformer TR. With relay NC de-energized and relay RC energized, a circuit is completed for operating the switch machine SM in a manner to reverse the track switch TS, which circuit may be traced from back contact 28 of relay CGS, wire 29,

front contact of relay RC, back contact 3| of relay NC, reverse control wire R, through the 1c; pe(rat)ing mechanism of the switch machine S It is to be understood that suitableapproach locking means is to be provided in the control circuits for the switch-machine SM, but in order to simplify the drawing, such locking means have been omitted. It was previously stated that the neutral contacts of relay WP are in their de-energized position whenever the track switch TS is not in either 'extreme locked position, and consequently during a change in position of the track switch the opening of the neutral front contact ll! of relay WP will de-energize the indi cating line wire IL; The opening of front contact I 8 obviously drops' relayNI which in turn drops relay NIS, but the indicating light COR is maintained energized overa circuit from back contact 54 of relay RIS, wire 55, back contact 56 of relay NIS, wires 51 and 41, through the light COR to It is thus obvious that an unlocked condition of the switch TS will be indicated at any time by dropping relays NIS and RIS and energizing the indicating light, COR at the control office. 7 I 7 When the reverse operation of the track switch has been completed the polar contacts ofv relay WP are shifted to their extreme right hand position and the neutral front contact I! is closed. A circuit is then completed for energizing relay RI at the control office with half cycles of alternating current of a reverse polarity (which may be termed polarity), and this energizing circuit-may be traced from the lower terminal of the secondary of transformer TR, over the common line wire C through the rectifying unit RB to bus B wire 38, front contact 39 of relay M, wire 31, polar contact l6 of relay WP in its right hand position, wire neutral front contact 8 of relay WP, indicating line wire IL, wire 36, through the windings of relaycPlI, wire 35, bus B, through the rectifying unit RB to the upper terminal of the secondary of transformer TR. The energization of relay RI now effects the picking up of relay RIS over a circuit from front contact 48 of relay RI, wire 49, back contact 59 of relay NIS, wires 5| and 52, through the windings of relay RIS to The picking up of relay RIS now indicates at the control office that the track switch TS has operated into correspondence with the reverse position R of the lever SML by extinguishing the indicating light COR as will be seen from observing its previously traced energizing circuits.

It will now be considered that, after receiving an indication of the reverse operation of the switch TS, the operator at the control ofiice moves the signal control lever SGL to position E for allowing an east bound train movement onto the passing siding. Thecontrol line circuit including line wire CL is now energized with alternating current, or in other words the half cycles of alternating current of the polarity are applied through rectifiers RA and RA to pick up relay NC at the field station, and these half cycles of alternating current of the polarity are alternated with half cycles of alternating current of the polarity through rectifiers RB andlRB to also pick up relay RC.

The energizing circuit for relay RC may be traced from the lower terminal of the secondary of transformer TR, over the common line wire C, through the rectifier RB to bus B wire 26, through the windings of relay RC, wire 21, control line wire CL, wire 5, back contact 60 of relay NIS, wire 6|, front contact 62 relay RIS, wire 63, contact 64 of the control lever SML in its reverse position R, wires 65 and 66, contact 61 of lever SGL in position E, bus B, through the rec- I tifier RB to the upper terminal of the secondary l of transformer TR. Likewise, the energizing circuit for relay NC may be traced from the upper terminal of the secondary of' transformer TR, through the rectifier RA to bus A, wire 68, contact 69 of the control lever SGL in position E, wire 10, back contact H of relay SA, wires 12 and 65, contact 64 of the control lever SML in position R, wire 63, front contact 62 of relay RIS, wire 6|, back contact 60 of relay NIS, wire 9, control line wire CL, wire l8, through the windings of relay NC, wire bus A through the rectifier RA and back to the lower terminal of the secondary of transformer TR over the common line wire C.

With both relays RC and NC energized, a circuit is completed for picking up relay CGS at the field station from front contact 14 of relay NC, front contact E5 of relay RC, through the winding of relay CGS to However, during the energization of the control line circuit with alternating plus and minus polarities,

energized over a circuit from back contact 43 of relay NIS, wire 42, front contact 4| of relay RIS, wires 16 and 11, contact 18 of the lever SML in position R, wire 19, contact of lever SGL in position E, wires 8| and 82, through the windings of relay SA to After a predetermined period of energization, the relay SA picks up and removes the half cycles of alternating current of the polarity from the control line circuit by opening its back contact H, which obviously drops relay NC at the field station but maintains relay RC energized due to the half cycles of alternating current of the polarity maintained on the line circuit through contact 61 of the control lever SGL.

Although the previously traced energizing circuit for relay CGS is now interrupted by the dropping of relay NC, a stick circuit is effective to hold up this relay from front contact 83 of relay RC, front contact 84 of relay CGS, through the windings of relay CGS to A circuit is now completed at the field station for selecting signal ES from front contact 28 of relay CGS, wires 85 and 86, contact 81 of relay NC, front contact 88 of relay RC, through the local signaling circuits as represented by the dotted line 89 to the signal ES.

It will now be obvious that a west bound signal may be selected in a similar manner, or that is, with the signal control lever SGL operated to its clear west bound position W, the control line circuit CL is energized for a predetermined period of time with alternating and polarities of energy to pick up both relays RC and NC, but after the relay SA at the control office picks up, the polarity of half cycles of alternating current will then be removed to drop relay RC and select relay NC. A relay CGS being selected by the previous application of both and polarities will noW be maintained energized by the previously traced stick circuit now completed by contact 98 of relay NC, and an obvious circuit for selecting the west bound signals according to the position of the track switch repeating relay WP will then be effective to allow, a, west bound train movement dependent of course on local conditions.

A signal repeating relay M at the field station is dropped as previously stated Whenever any one 5' of the signals is displaying a clear indication, and keeping in mind the previous energization of the indicating line circuit with polarity of half cycles of alternating current to pick up relay RI and its stick repeating relay RIS at the control office, it will be obvious from the drawing that this dropping of relay M changes the polarity of the half cycles of alternating current from to by the dropping of contact 39 which shifts the line wire LI from bus B to bus A This quick changing from to polarity of half cycles of alternating current in the indicating line circuit obviously drops relay RI and picks up relay NI, and inasmuch as there is substantially no intervening time between the dropping of relay RI and the picking up of relay N1, the relay RIS having slow releasing characteristics does not drop due to a stick circuit completed by the picking up of relay NI. This stick circuit may be traced from front contact 2| of relay NI, wire 22, front contact 23 of relay RIS, wires 9| and 52, through the windings of relay RIS to This out-of-correspondence condition between the energization of the line relays at the control the slow acting relay SA at the control office is ofiice and their respective repeatingrelays; or that is, with relay RIS energized but with relay NI energized instead of relay. RI, an indication that a signal is clear at the field station, is given;

at the control ofiice by energizing the indicating light SK over a circuit from back contact 43 r of relay NIS, wire 42, front contact 4| of relay 'RIS, wires 16, and 92, front contact 93 of relay NI, back contact 94 of relay RI, wire 95, through the indicating lightSK to front contact 48 of relay RI, wire49, front contact 50 of relay NIS, wires 96 and"25, through the winding of relay N18 to With relays RI and NIS energized, an indication of a clear signal is given by energizing the indicating light SK over a circuit from back contact 4| of relay RIS, wire 42, front contact 43 of relay NIS, wires 44, 91 and 98, front contact 94 of relay RI,

back contact 93 of relay NI, wire 95, through the indicating light SK to Having now described the way in which the track switch TS may. be controlled from the control ofilce and the manner in which a signal governing movements over this switch may be cleared, it will be considered that a train enters the section of track including the switch TS thereby dropping the relay TR. The contact l6 of relay WP which selects the particular polarity oi half cycles of alternating current to indicate the position, of the track. switch is then con-' "nected in multiple with a contact l of relay WP by back contact Illl of relay TR. It may be'seen from the drawing that this contact I00 is connected in an opposite manner to contact [6, and consequently regardless of. the position of the contacts of relay'WP, the wires I4 and 31 are each' connected to the line wireIL whenever therelay TB is ole-energized. Thus, the occupancy of the track section controlling relay TR is effective to apply full cycles of alternating current through both rectifiers RA and R3 to the line wire IL, or for example, with the track relay TR de-energized and relays WP and M in the position shown, the line wire IL is energized with half. cycles of alternating current of the polarity through front contact l8 of relay WP, wires'll and I02, back contact'lfll of relay TR, contact 993 of relay WP in its left hand position wires I03 and 31, front contact 39 of relay M, wire 38 to bus B and rectifier RB and likewise the line wire IL is energized with half cycles of the polarity through front contact I8 of relay WP, wire I1, contact I6 of relay WP in its left hand position, wires l and I4, front contact 13 of relayM, 'wire'lZto bus A d and rectifier RA The half cycles of alternating current of the plus polarity are effective at the control office to pick up relay NI, and simultaneously the half 7 cycles of alternating current of the minus polarity alternating therewith are effective to pick up relay R-I. An indication'of the occupancy of the track section at the field station is now given at the control cflice by energizing the'ind icating light OS over a circuit It will be obvious that, when the track'rel'ay TR is dropped, the signal governing trafiic movesv ments over the track section are placed at stop by the local block signalling circuits thereby picking up relay M, and at the control ofiice, the signal indicating light SK is de-energized at either back contacts 93 or 94 of relays NI or RI respectively, which are now both energized. However, an indication of the correspondence between the track switch and the control lever SML is retained by the energization of relay RIS, and as soon as the'train progresses out of the track section, the relay 'I'R will again pick up to allow the energization of the indicating line circuit to be selected in accordance with the operated position of the track switch TS, which in this case will be the reverse position to select relay RI and maintain relay NIS energized.

If during the existence of a clear signal indication at the field station the operator desires to place such a signal at stop, the signal control 'lever SGL is returned to the stop position S both de-energized which drops relay CGS there by opening the signal control circuit at contact 28. When the relay SA drops, the control line circuit is again closed by back contact 1 of relay SA, and the energization of the control line circuit is again selected in accordance with the position of the switch control lever SML. It will be obvious that the control circuit set up by moving the signal control lever SGL to either the clear east bound or clear west bound position may only be effective when an indicatlon of the operated position of is present at the control ofiice which corresponds to the position of a switch control lever SML or in other words, the selected energization oi relays N15 and RIS in regard to'the position of contact 60 and 62 must correspond to the position of contact 64 of lever signal control circuit can be completed. Also to prevent the cancelling of a switch control which has not been executed by a subsequent movement of the signal control lever, the same correspondence arrangement is employed in series with the energizing circuit for relay SA, or that is, the selected energization of relays N18 and RIS in regard to the position of contacts 43-and 4I- must correspond to the position of the switch control lever contact 18 before the relay SA may be picked up to open the switch control circuit and back contact'l.

the switch control lever before a signal control can be effective obviously permits a route to be the track switch SML before the aligned by the operator by positioning the switch control lever and immediately thereafter moving the signal control lever to set upa control for a clear signal in the selected direction, in asrnuch as such signal control will not be elTective until an indication has been received at the controlofiice that the track switch ha s operated a circuit completed when both the series line relays are picked up.

The above rather specific description of one form of the present invention is given solely by the way of example, and is not intended in any manner whatsoever in a limiting sense. It is also to be understood that various modifications, adaptations, and alterations may be applied to meet the requirements of practice, without in any manner departing from the spirit or scope of the present invention except as limited by the appended claims.

Having thus described my invention, what I claim is:

1. In a centralized trafi'ic controlling system for railroads, a control office, a field station, a line circuit connecting said control ofiice and said field station, a means for controlling a first device at said field station by selecting the direction of pulsating current in said line circuit, a means for controlling a second device at said field sta, tion by selecting the direction of pulsating current in said line circuit, and means for changing the control of said first device to the control of said second device by momentarily energizing said line circuit with alternating current.

2. In a centralized traflic controlling system for railroads, a control office, a field station, a line circuit connecting said control ofiice and said field station, an alternating current source of energy for energizing said line circuit, a first control lever at said control office arranged to selectively energize said line circuit with either polarity of half cycles of alternating current, a second control lever at said control oflice arranged to selectively energize said line circuit with either polarity of half cycles of alternating current only after a momentary energization of said line circuit with full cycles of alternating current, a track switch at said field station controlled in accordance with the polarity of half cycles of alternating current applied to said line circuit, and means for shifting from the control of said track switch to the control of directional signals at said field'station when said line circuit is energized with full cycles of alternating current.

3. In a centralized trafiic controlling system for railroads, a control ofiice, a field station, a control line circuit connecting said control ofiice and said field station, two control relays at said field station, a plurality of devices at said field station, means at said control office for energizing either of said control relays over said control line circuit, to control a first of said devices and for momentarily energizing both and then de-energizing either of said control relays to change the control from said first device to a second of said devices at said field station.

4. In a centralized trafiic controlling system for railroads, a control office, a field station, a line circuit connecting the control ofiice and the field station, an alternating current source of energy, means at said control ofiice and at said field station for dividing said line circuit into two branches at said control oifice and at said field station, a relay in series with each of said branches at the field station, means at said control office and at said field station permitting current to fiow only in one direction in one of said branches and only in the other direction in the other of said branches at said control office and said field station, means for energizing either of said branches to efiect the control of a first device at said field station, means for momentarily energ izing both of said branches and subsequently de-energizing one of said branches to effect the control of a second device at said field station.

5. In a centralized trafiic controlling system for railroads, a control o ifice, a distant field station, a line circuit connecting said control office and said field station, a switch control lever at said control oflice, a means for selecting the direction of pulsating current in said line circuit in accontrol lever when said slow acting relay is picked up, a track switch and associated signals at said field station, control means for said track switch and signals associated with said line circuit and means for shifting said control means from said track switch to said signals when said line 011- cuit is energized with alternating current.

6. In a railway centralized traffic controlling system, a control ofifice, a distant field station, a line circuit connecting said control office and said field station, a switch control lever arranged to energize saidline circuit with either direction of pulsating current, a signal control means at said control ofiice operable to momentarily apply alternating current and to subsequently apply either direction of pulsating current to said line circuit, a first control relay at said field station energized by one direction of pulsating current in said line circuit, a second control relay 'at said field station energized by the other direction of pulsating current in said line circuit, a control selecting relay energized when said first and said second control relays are both energized, a stick circuit for said control selecting relay completed when either of said control relays are energized, a track switch and associated signals at said field station, contacts on said control relays arranged to control said track switch when said control selecting relay is de-energized and contacts on said control relays arranged to control said signals when said control selecting relay is energized.

7. In a centralized traific controlling system for railroads, a control ofilce, a field station, a line circuit connecting said control office and said field station, a track switch and associated signals at said field station, switch and signal indicating means at said control office, a track relay at said field station, a track indicating means at said control office, means for conditioning said switch indicating means by selecting the direcenergizing said line circuit with alternating curin accordance with the new position of the switch control circuit as well as the energizing circuit for relay SA as previously described, but when the relay ,SA has once picked up and allowed a particular signal to be selectively cleared, asubsequent movement of the switch control lever will neither open the signal control circuit nor drop the relay SA. This is accomplished by a stick circuit effective to hold up relay SA whenever contact we of lever SGL is in either clear position through a front contact I01 of relay 'SA, and with the relay SA energized the signal control contact 6'! of'lever SGL is always connected to the control line wire CL by wires, 65 and I08, front contact 'l of relay SA and wires 8 and 9.

Summary 7 with half cycles of alternating current, which half cycles are of a uniform polarity which is selected by a contact of the switch control lever through either one of two oppositely arranged rectifiers. The field station end-of the control line circuit isdivided into two branches, one branch being arranged to conduct one polarity of half cycles of alternating current only by a series rectifier, and the other branch being arranged to conduct the other polarity of half cycles of alternating current only by an oppositely arranged rectifier. Two relays, one in series with each of these branches at the field station, are then selectively energized in accordance with the" position of the switch control lever and their position is effective to control the track switch. It is obvious that both of these series relays at the field station may be energized by applying full cycles of alternating current to the control line circuit, and consequently when a clear signal control is set up at the control oflice by the switch control 'leverthe field station apparatus is conditioned for the reception of the signal control instead of the switch control by the application of full cycles of alternating current for a predetermined length of time which picks up a control selecting relay at' the field station, after which one polarity of half cycles of alternatingcurrent is removed from the control line circuit,

'and the series line relay remaining energized is effective to stick up the control selecting relay and select the clearing of a signal in the. direction corresponding to, the position of the switch control lever. In canceling a signal: clear control,

the control line circuit is de-energized for a predetermined period in which the control selecting relay is dropped at the field station thereby allowing a following energization of the control line circuit to be of a polarity of half cycles or alternating current which is in accordance with the position of the switch control lever.

Indications of the condition of various apparatus at the field station are transmitted to the control office over an indicating line circuit which is substantially the reverse arrangement of the control line circuit, or that is, the indicating line circuit is selectively'energized at the field station with either polarity of half cycles or with full cycles of alternating current, and at the control office, the indicating line circuit is divided into two branches each including a series relay and oppositely arranged rectifiers in the same manner as the field station end of the control line circuit. The same rectifiers at both the control ofilceand field station may be employed in both the control and indicating circuits as shown, or of course, separate units may be provided. v, r

The communication of indications of the switch position is accomplished by selecting a definite polarity of half cycles of alternating current in accordance with/the operated position of the track switch thereby selecting only one'ol the series line relays at the control office. Each series line relay at the control ofiice is provided with a slow acting stick repeating relay, which two repeating relays may control a correspondare de-energized for a period of time before the new series relay is selected which allows the selection of the slow-acting repeating relays to follow in accordance with the selection of, the

series line relays. However, in indicating a clear signal, the polarity of thehalf cycles of alternating current is quickly changed without an intervening period of de-energization of the indicating line circuit which does not allow the selection of the slow acting repeating relay to follow in accordance therewith and consequently the selection of the series line relays is out of correspondence with the energization of their slow acting repeating relays. .A signal indicating light at the controlofiice is then energized by a circuit completed by this out-of-correspondence condition between the series line relays and their stick repeating relays, but when the clear signal at the field station is returned to stop, the polarity on the indicating line circuit is changed back to its original polarity of half cycles of alternating current thereby extinguishing'the clear signal indication at the control office by operating the series line relays into correspondence with the energization of their stick repeating relays. 7

An' indication of a third device at the field station, which may be a track relay, is transmitted to the control oflice by a circuit arrangement whereby the full cycles of alternating current are applied to the indicating line circuit in the same manner as described in connection with the control line circuit. These full cycles of alternating current are efiective at the control oflice to pick up both series line relays, and an indication of the dropping of the track relay at the field station is given by an indicating light energized by r." I O system, a control oflice, a field station, a line circuit connecting said control ofiice and said field station, a first line relay at said control ofiice energized by one direction of current in said line circuit, a second line relay at said control oifice energized by the other direction of current in said line circuit, a first slow acting relay picked up by said first line relay, a second slow acting relay picked up by said second line relay, stick circuit means for maintaining either of said slow acting relays energized when the direction of current in said line circuit is quickly changed after such slow acting relay is picked up, a plurality of indicating means at said control ofiice controlled by said slow acting relays, and means for causing current to fiow in said line circuit in one direction, in the other direction, in each direction alternately, for opening said line circuit or for quickly changing the direction of current in accordance with various conditions at said field station to distinctively control said indicating means at said control office.

9. In a railway centralized traflic controlling system, a control oflice, a field station, a first line circuit connecting said control ofiice and said field station, artrack switch and associated signals at said field station, an alternating current source of energy, means including rectifiers at said control oifice and rectifiers at said field station for controlling either said track switch or said signals from said control office in accordance with the energization of said first line circuit, a second line circuit connecting said control office and said field station, and means including rectifiers at said control ofiice and rectifiers at said field station for indicating at said control office the position of said track switch and said signals and the presence of a train on said track switch in accordance with the energization of saidsecond line circiut.

10. In a railway centralized controlling system, a control ofiice, a field station, a track switch and associated signals at said field station, a track switch control lever and a signal control lever at said control office, a first line circuit and a second line circuit each connecting said control office and said field station, means for indicating at the control office the condition of said track switch and associated signals over said second line circuit, means for controlling said signals over said first line circuit only when the indi cated condition of said track switch corresponds to the position of said track switch control lever, and means for controlling said track switch over said first line circuit only when said signals are placed at stop.

11. In a railway centralized trafiic controlling system, a control oifice, a field station, a track switch and associated signals at said field station, a track switch control lever and a signal control lever at said control oifice, a first line circuit and a second line circuit each connecting said control office and said field station, means for indicating at the control ofiice the condition of said track switch and associated signals over said second line circuit, means for clearing said signals over said first line circuit only when the indicated condition of said track switch corresponds to the position of said track switch control lever, means for retaining an existing cleared signal irrespective of a subsequent movement of said track switch control lever, and means for controlling said track switch by said track switch control lever over said first line circuit.

12. In combination, a control point, a distant location, two line circuits connecting said control point and said distant location, rectifier units at said control point and at said distant location, means including one of said line circuits and said rectifier units for controiling a plurality of devices at said distant location from said control point, and means including the other of said line circuits and said rectifier units for indicating at the control point the condition of said plurality of devices at said distant location.

13. In combination, two spaced locations, a line circuit connecting said spaced locations, first and second devices at one of said spaced locations, means for at times controlling said first device by energizing said line circuit with pulsating current of one or the other polarity at said other location, means for at times controlling said second device by energizing said line circuit with pulsating current with one or the other polarity at said other location, and means for automatically selecting whether said first or said second device is to be controlled by the particular energization of said line circuit.

14. In combination, two spaced locations, a line circuit connecting said spaced locations, first and second devices at one of said spaced locations, means for at times controlling said first device by energizing said line circuit with pulsating cu-rrent of one or the other polarity at said other location, means for at times controlling said second device by energizing said line circuit with pulsating current with one or the other polarity at said other location, and means for determining that said second device is to be controlled, which means is rendered effective by temporarily energizing said line circuit with alternating current.

15. In combination, two spaced locations, a line circuit connecting said spaced locations, firstand second devices at one of said spaced locations, means for at times controlling said first device by energizing said line circuit with pulsating current of one or the other polarity at said other location, means for at times controlling said second device by energizing said line circuit with pulsating current with one or the other polarity at'said other location, means for determining that said second device is to be controlled, which means is rendered effective by temporarily energizing said line circuit with alternating current, and means for determining that said first device is to be controlled, which means is rendered effective by temporarily deenergizing said line circuit.

16. In combination, two neutral relays which can be selectively controlled so that either or both may be energized or both may be deen'ergi'zed, a first and a second device, means for distinctively controlling said first device in accordance with which particular one of said relays is energized after both said relays have been deenergized, and means for distinctively controlling said second device in accordance with which particular one of said relays is energized after both of said relays have been energized.

17. In combination, two neutral relays which can be selectively controlled so that either or both may be energized or both may be deenergized, a first and a second device, means for distinctively controlling said first device in accordance with which particular one of said relays is energized only after both said relays have been deenergized, and means for distinctively controlling said second device in accordance with which particular one of said relays is energized only after both of said relays have been energized.

18. In combination, two neutral relays which 'tained energized by energization by either of said neutral relays, a, first and a second device, means for selectively controlling said first device in accordance with the selective energization of said neutral relays when said stick relay is deenergized, and means for selectively controlling said second device in accordance with the selective energization of said neutral relays when said stic relay is energized. r

19. In combination, two neutral relays which can be selectively controlled so that either or both may be energizedor both may be deenergized, two slow acting stick relays, a pick up circuit for one of said stick relays including a front contact of one 'of said neutral relays and a back contact of theother'of said stick relays, a pick up circuit for said other of said stick relays including a front contact of the other of said neutral relays and a back contact, of said one stick relay, a stick circuit for said one stick relay including its own front contact and a front contact of said other neutral relay, a stick circuit for said other stick relay including its own front contact and a front contact of said one neutral relay, and

" electro-responsive means controlled by said relays jointly.

20. In combination; a, line circuit connecting two spaced locations; two manually operable levers at one of the locations, each of said levers for at times selectively energizing said line circuit with pulsing current'of one polarity or the other;

electro-responsive means at the other of the 10- cations distinctively responsive to the polarity of energization of said line circuit; means at the one location for at times automatically causing said line circuit to be successively energized in accordance with said two manually operable levers with an intervening energization of alternating current on said line circuit; first and second devices at the other location, said first device being normally under the control of said electro-responsive means; and means controlled by said electro-responsivemeans during the energization of said line circuit with alternating current for automatically causing said second device to be placed under the control of said electro-responsive means. 21. In a centralized traflic controlling system for railroads; a track switcho perable to normal and reverse positions; a signal for governing traf- V fic over said track switch; a switch control lever having normal and reverse positions; a signal control lever having clear and stop positions; a selector relay; a pick up circuit for said selector relay closed only when said track switch and switch control lever are in corresponding normal or reverse positions and said signal lever is in a' clear position; a stick circuit for said selector relay including its own front contact and a contact 7 on said signal lever closed when such signal lever is in a clear position, whereby said relay when once picked up is fully dependent for its energizer.

tion on said signal lever; means for controlling said track switch by said switch lever effective only when said selector relay is deenergized; and means 5 for controlling said signal by said signal lever effective only when said selector relay is picked up.

22. In a centralized traffic controlling system for railroads; a control office; a field station; a line circuit connecting said control ofiice and said field station; an alternating current source of energy for energizing said line circuit; a'rail'road track switch at the field station; a signal atthe field station; switch contacts operated by said track switch to normal, reverse and open unlocked positions; means including said switch contacts for selectively allowing said line circuit to be energizedfrom said source with either polarity of half cycles of alternating current in accordance with the position of said track switch or to be deenergized; signal contacts operated in accordance with the condition of said signal; means includingsaid signal contacts for reversing the polarity of ener gization of said line circuit with half cycles of alternating current applied through said switch contacts, whereby said switch contactsimay reverse the polarity of half cycles only after a prolonged deenergization of said line circuit, and

whereby said signal contacts can quickly reverse,

the polarity of energization of said line circuit; electro-responsive means at the, control ofiice responsive to the polarity of energization of said line circuit; means controlled by said electro-re-I sponsive means to register whether a reversal of polarity on said line circuit has been after a prolonged deenergization or has been quickly accomplished; and indicator means controlled by said electro-responsive means and said registering means.

EDWIN O. BLODGE'I'I.

DISCLAIMER 2,042,450.Edmn O. Blodgett, Rochester, N. Y. CENTRALIZED TRAFFIC CONTROL- LING SYSTEM FOR RAILRoADs. Patent dated June 2, 1936. Disclaimer fil'ed April 12, 1937, by the assignee, General Railway Signal Company.

Hereby enters this disclaimer by disclaiming from claim 1 any system, except wherein the means for controlling a first device and the means for controlling a second device are separately and independently operable manually; by disclaiming from claims 13 and 14 any system, except wherein the means for at times controlling said first device and the means for at times controlling said second device are separately and independently operable manually; by disclaiming from claim 9 any system, except wherein the second line circuit includes a different line Wire connecting the control oflice and the field station than is included in the first line circuit; and by disclaiming from claims 16 and 17 any system, except wherein the devices defined as a first and a second device are a switch machine and signals associated with said switch machine.

[Ofiicial Gazette May 11, 1.987.] 

